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No Drawing.

'vision of a new and imp .tain of the ingredients ing' out the PatentedSept- 1 1932 UNITED. STATES PATENT ori-" ce rAuI. s. rsnnme, or mm,

ILLINOIS, nssrenon ro rnnnnam E. SCHUNDLEB, or

sonar, ILLINOIS rziocn'ss' or cononme GRANULAB AND o'rnnn MATERIAL Thisinvention relates to the method of coloring anules and'other n'1aterial.

One of the Objects of the invention is the provision'of a new andimproved. method of coloring granules and the like, whereby a g coloringgranules formed in an eificient'and economical manner.

Other and furtherobjects and advantages of the invention. will appearfrom the ollowing description.

In carrying out the process, the granular or other' material'after beingcleaned has thoroughly mixed with it in adry state a small quantity of aslightly water soluble pounds=to' each ton of compoun on a solublesilicate'to form an Insoluble compound such for instance as calciumoxdrated calcium sulphate 1d6.- A e amount of. the calcium compound, for

, oring mixture.

d that has the property of reacting ide, magnesium oxide, hydrated ordehyor calcium hydroxinstance, may vary within wide limits, but it hasbeen found by experiment that about ten anular material gives excellentresults. or convenience in description this. compound be termed thefixing compound.

,' To this 'xture is'added a' mixture containing the coloring matter,which for convenience of description will be termed a col- Thecoloring'mixture may v The folbe repared in'numerous ways.

lowing gives satisfactory results:

- .This is preferably ter is then added and 'g'ment and bentonite. onein a ball mill. Wa-

the whole thoroughly Dry mix color mixed as m a conventional spiralpaint m xer Application med June a1, 1a29. Serial no. 312503.

or the like. Since there is no chemical reaction among the elementofthis mixture the proportions may vary within wide limits.

The. following has been found to give very ood results:

. The following formula is given as illustra tive of the proportions ofingredients for coloring granular material. For each ton of the materialtobe colored red, for instance,

mix-the granular material with ten pounds a of the fixing compound, as acalcium compound, then add the following previously prepared mixture:oxide of iron, 8 pounds of Bentonite, 60 poginds of water, 90 pounds ofsodium silica e, thoroughly and finally dry the coated granules.

The above, expressed in percentages, would be about as follows:

Granules about; 91.8 plus Fixing compound about .45 plus Color pigmentabout .45 plus Bentonite about .36 plus Water about 2.74 plus Solublesilicate about 4.13 plus purpose of holding the color pigment insuspension in the solution, whereb uniformity of'color is insured. Anyother ely divided or. colloidal material may be. employed, as china clayand the like. Of the colloidal clays, Bentonite gives the best resultsin that a much smaller amount is required. probably due to the fact thatits percentage of colloidalmatter is much higher than most othercolloidal clays. Materials that have been peptized may also be usedinstead of the Bentonite.

The ingredients of the may b mixed in any order, but forpractical work,taking everything in consideration,.the

to form the coloring mixture, then mix Thisi's coloring mixture- 10pounds of O. P. red

The -Bentonite is employed solely for the order of the steps given aboveis preferred, at

resent."

- After the-coloring mixture is prepared it is mixed with the granularmixture and then dried at temperatures ranging from say 3009 or 350 F.to around 600 F., depending on the coloring material employed. somecoloring material, 'as for. instance hydrated ferrous oxide thetemperature must be kept below 360 F., otherwise the color will bedestroyed b being changed from golden yel-' low to pin The maximumdrying temperature will depend to a great extent 'on the nature of thecoloring pigment employed. It must be kept below that point Where thecolor will not be affected. It is in all.cases-above the boiling pointof water, but in most cases it is preferably not above 600 F. The fixingmaterial reacts on the silicate to form an insoluble silicate.

"The objectof the drying process is to facilitate the reaction betweenthe soluble silicate and the fixing-compound, and also to dehy drate thesodium silicate not reacted 'on and the calcium orother silicate formedby said reaction. Vvhenheatcd above the boiling point'of water thesesilicates will .lose all but. about 3% ,of their water of crystallizaftion, with the result that the color pigment is permanently secured tothegranules without impairing the intensity or tints of the coloringmatter, and the coating is rendered'highly insoluble.

"Itwill thus be seen that a process for coloring granules is providedwhereby the coloring matter may be both applied and fixed to thegranular material, simultaneously.

While the specific formula for coloring granules given above is atpresent preferred reduced. For instance, in the above formula the colorpigment may be reduced from eight or ten pounds to six pounds, thereby.accomplis hing a decided saving in the cost of coloring the granulessince the color pigments are costly. When it' is desired to repeat theprocess the formula given 1 above remains the same except that threepdunds of oxide of iron aresubstituted for the ten pounds given in theformula for eachcoat applied to the granules. In other words, for .the

two coats twice the am ountgof Bentonite,

water, sodium silicate and the calcium compound is used, but only sixpounds of oxide of iron is necessary to give each ton of granules twocoats of coloring material. The intensityof the color by this doubletreatment, using only six pounds of the coloring matter, issubstantially the same as ten pounds where only one coat is applied.

The pigment appears to be more firmly Y renew aflixed, which isprobablyl due to the fact that after the first coating t ere is more orless free soluble silicate on the surface of the material, and thisbeing again coated, firstwith the calcium or magnesium compound and thenwith the coloring matter and soluble silicate, the fixin solublesilicate ofioth coats, i. e. it acts from without on the first coat andfrom within on the second.

While the formula given above gives good results it is understood thatthe proportion compound .reacts on the of the compounds, used may'varyeonsiderably and that other color pigments may be employedto secureother colors, as desired.

'1 claim as my invention:

1. A method of coloring granules which consists in mixing in a dry'stategranular material and a substance that will react on a soluble silicateto form an insoluble silicate,

then applying a mixture of'coloring matter and 'a soluble silicatesolution and finally drying the mixture by artificial heat.

2. A method of coloring granules which consists in mixingin a dry stategranular material and a fixing compound, then adding asolutioncontaining a coloring pigment and a soluble silicate, and then dryingthe mass at a temperature above that boiling point of water but belowapproximately 600 F.

3. A. method of coloring granules which consists in mixing in a drystate granular ma.-

terial and a substantially insoluble material that will convert asoluble into an insoluble silicate, and then mixing the same with acoloring mixture comprising coloring matter and a soluble silicate, andthen drying the mass by heat above the boiling'point of water but belowapproximately 600 F.

4. A method' for coloring granules which consists in mixing a slightlywater soluble compound that will react on a soluble silicate to form aninsoluble silicate with granular material in substantially the followingproportions ten pounds of'the. former to two thousand pounds'of thelatter; then treating this mixture with a coloring compositioncomprising:

. Pounds (l. P. oxide of iron Bentonite 8 Water Sodium silicate 90 thendrying the mixture at a heat above that of boiling water but below thepoint wherethe color pigment will be affected by the heat,

and thenrepeating the process.

In testimony whereof ll aflix my si ature.

PAUL S. DE ING.

